Effects of Stearic Acid on Tensile, Morphological and Thermal Analysis of Polypropylene (PP)/Dolomite (Dol) Composites

The effects of stearic acid treated dolomite (Sa-Dol) on the mechanical, morphological and thermal properties of polypropylene (PP) composite were studied. Prior treatment, raw dolomite was ground in planetary mill using different grinding time to obtain the submicron size (under 10µm). Particle size and specific surface area of dolomite was analyzed and validated using particle size analyzer (Malvern Mastersizer) and BrunauerEmmett-Teller (BET) method respectively. Dolomite with five filler loadings (5, 10, 15, 20 & 25%) were mixed with PP thermoplastic and were compounded using hot melt blending method. Fourier Transform Infrared (FTIR) spectroscopy confirms the successful of filler treatment using stearic acid according to the new peak at 2917 cm --1 attributed to the alkyl group that represented the addition of C-H bond. Tensile properties indicated that tensile strength of PP/Dol decreased with the increasing of filler loading for both systems. The elongation at break decreased with filler loading and showed better and improved result after treatment with stearic acid. The incorporation of stearic acid coated filler into PP matrix enhanced the break elongation of the composites that makes the composites more ductile. Morphological analysis using Scanning Electron Microscopy (SEM) proved better interfacial adhesion and less agglomeration of dolomite filler after treatment with stearic acid at low filler loading (5 wt.%)

Hydrogen adsorption on pristine, defected, and 3d-block transition metal-doped penta-graphene

© 2016 Hydrogen Energy Publications LLC The effects of different crystallographic defects and substitutional doping of 3d-block transition metals (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn) on the electronic properties and hydrogen molecule (H2) interaction of penta-graphene (PG) were investigated using density functional theory calculations. Electronic properties of PG show strong dependence on PG\u27s structural configuration and the type of metal dopants used. Doping PG with transition metals (TM) may be used to change PG from being a wide band gap semiconductor to a narrow band gap semiconductor or a semimetal. PG have H2 adsorption energies (Eads) that are superior to graphene, with Eads between −0.7 eV and −0.9 eV depending on the adsorption site. Transition metals act as proton rich dopant, and induced positive electrostatic potential in its adjacent regions. Thus, doping improve H-2 adsorption, especially when substituted on sp2 hybridized carbon site. The V-doped and Ti-doped sheets, with Eads of −0.351 eV and −0.319 eV, respectively, show the greatest potential for on-board reversible solid-state hydrogen molecule storage application

First principles investigation on H2 adsorption on the pristine 2-dimensional hexagonal aluminum

Lightweight hydrogen storage with high storage capacity is one of the challenges in pursuing a hydrogen economy as a source of clean energy. Aluminum has been proposed as a material for storage and production of hydrogen. Recent theoretical studies have established the feasibility of 2D hexagonal lattice structure aluminum. In this study theoretical investigation on 2D h-aluminum was performed employing density functional theory to study the energetics of hydrogen molecule and 2D h-aluminum system. Hydrogen molecule on top, hollow and bridge sites of hexagonal lattice were geometrically optimized to determine if hydrogen molecule would dissociate or adsorbed as a molecule. Results showed that hydrogen molecule can be physisorped mainly in the bridge site (-0.463 eV) at a distance of 3.1 Å, while it can dissociate at the top site with an activation energy of 1.51 eV. Electron density difference shows transfer of 0.60e- from hydrogen atoms to the aluminum atoms. Density of states showed broadening of energy levels and their general shift towards lower energies, and alignment of the orbitals showing sp hybridization. Results of this study can be used in further investigation on doped or decorated systems of 2D h-aluminum. © Published under licence by IOP Publishing Ltd

Theoretical investigation on the solubilization in water of functionalized single-wall carbon nanotubes

An important technique to increase the solubility and reactivity of carbon nanotube is through functionalization. In this study, the effects of functionalization of some single-walled carbon nanotubes (SWCNTs) were investigated with the aid of density functional theory. The SWCNT model used in the study consists of a finite, (5, 0) zigzag nanotube segment containing 60 C atoms with hydrogen atoms added to the dangling bonds of the perimeter carbons. There are three water-dispersible SWCNTs used in this study that were functionalized with (a) formic acid, as a model of carboxylic acid, (b) isophthalic acid, as a model aromatic dicarboxylic acid, and (c) benzenesulfonic acid, as a model aromatic sulfonic acid. Binding energies of the organic radicals to the nanotubes are calculated, as well as the HOMO-LUMO gaps and dipole moments of both nanotubes and functionalized nanotubes. Binding was found out to be thermodynamically favorable. The functionalization increases the electrical dipole moments and results in an enhancement in the solubility of the nanotubes in water manifested through favorable changes in the free energies of solvation. This should lower the toxicity of nanotubes and improve their biocompatibility. Copyright © 2012 Michael Mananghaya et al

Theoretical investigation on single-wall carbon nanotubes doped with nitrogen, pyridine-like nitrogen defects, and transition metal atoms

This study addresses the inherent difficulty in synthesizing single-walled carbon nanotubes (SWCNTs) with uniform chirality and well-defined electronic properties through the introduction of dopants, topological defects, and intercalation of metals. Depending on the desired application, one can modify the electronic and magnetic properties of SWCNTs through an appropriate introduction of imperfections. This scheme broadens the application areas of SWCNTs. Under this motivation, we present our ongoing investigations of the following models: (i) (10, 0) and (5, 5) SWCNT doped with nitrogen (CN x NT), (ii) (10, 0) and (5, 5) SWCNT with pyridine-like defects (3NV-CN x NT), (iii) (10, 0) SWCNT with porphyrine-like defects (4ND-CN x NT). Models (ii) and (iii) were chemically functionalized with 14 transition metals (TMs): Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pd, Ag, Pt and Au. Using the spin-unrestricted density functional theory (DFT), stable configurations, deformations, formation and binding energies, the effects of the doping concentration of nitrogen, pyridine-like and porphyrine-like defects on the electronic properties were all examined. Results reveal that the electronic properties of SWCNTs show strong dependence on the concentration and configuration of nitrogen impurities, its defects, and the TMs adsorbed. Copyright © 2012 Michael Mananghaya et al

H2O Absorptivity on a Fully 4-crosslinked Polyacrylamide Membrane via Density Functional Theory and Monte Carlo Calculations for Draw Solution Recovery in Forward Osmosis

© 2019 IEEE. The draw solution recovery process is a necessary step in forward osmosis systems, such as the one being applied in the dewatering of microalgae. Among the many draw solution recovery methods, the stimuli-response regeneration technique emerged to be one of the most promising in terms of energy efficiency. However, a material with an excellent capacity to absorb water would be needed for this type of process. This study investigated the water adsorption properties of 4-crosslinked polyacrylamide membrane (PAM) by means of density functional theory and Monte Carlo calculations for potential application in draw solution recovery. A geometrically optimized, stable, and energy minimized 4-crosslinked PAM model was prepared and allowed to be immersed to different amount of water molecules. The adsorption energies of water molecules on PAM were calculated. Results indicate that water molecules are most likely to be adsorbed on the amide groups of 4-crosslinked PAM. It was shown that the addition of lower number of water molecules had the highest probability of water molecules adsorbing on PAM. It was found that the 4-crosslinked PAM can adsorb a minimum of 75 and a maximum of 145 water molecules. Results of the study would be useful as a guide for the synthesis and further characterization of PAM for draw solution recovery in forward osmosis systems, specifically in microalgae dewatering

Revealing the water resistance, thermal and biodegradation properties of citrus aurantifolia crosslinked tapioca starch/nanocellulose bionanocomposites

© 2020, Springer Science+Business Media, LLC, part of Springer Nature. Moisture absorption, thermal and biodegradation properties of nanocellulose (NC) reinforced bionanocomposite tapioca starch (TS) films crosslinked with Citrus aurantifolia or lime juice (LJ) were investigated for food packaging applications. The films were synthesized by solvent casting using different amounts of nanocellulose and crosslinkers: lime juice and a commercial citric acid (CA). Nanocellulose as reinforcing filler was obtained from oil palm empty fruit bunches through acid hydrolysis. Crystallinity of all TS bionanocomposites was determined using X-ray diffractometry. TS bionanocomposites interaction with water was studied by means of moisture absorption, moisture content and swelling. Flory-Huggin model was used to measure the crosslinked density of crosslinked TS bionanocomposites which indicated successful crosslinking using LJ and CA for TS. The crystallinity of TS film increased from 43.5% for neat TS to 51.6% for TS film with inclusion of NC. LJ-crosslinked TS film with 1 wt% of NC (based on starch content) had the lowest moisture absorption and swelling ratio. TS bionanocomposites with LJ had better thermal and biodegradation properties compared to commercial CA-crosslinked TS biocomposites, which can be a potential food packaging material among the tested bionanocomposites

Ab initio study on hydrogen interaction with calcium decorated silicon carbide nanotube

© 2017 Hydrogen Energy Publications LLC Ab initio study on the viability of calcium decorated silicon carbide nanotube as a hydrogen storage material was conducted. Calcium strongly adsorbs on silicon carbide nanotube (SiCNT) with a significant binding energy of −2.83 eV, thus calcium\u27s low cohesive energy and strong binding with SiCNT may prevent Ca to form clusters with other adsorbates. Bader charge analysis also revealed a charge transfer of 1.45e from Ca to SiCNT resulting to calcium\u27s cationic state, which may induce charge polarization to a nearby molecule such as hydrogen. Hydrogen molecule was then allowed to interact with the calcium adatom where it exhibited charge polarization, induced by the electric field from calcium\u27s positive charge. This resulted to a significant binding energy of −0.22 eV for the first hydrogen molecule. Results reveal that Ca on SiCNT can hold up to 7 hydrogen molecules and can be a promising candidate for a hydrogen storage material

A dynamic Leontief model with stochastic extensions for sustainable jatropha curcas biofuel supply chain

Jatropha biofuel is an excellent candidate for an alternative renewable and clean energy source. However, an increasing number of countries and investors are losing interest in J. curcas mainly because of the challenges they encountered caused by ineffective organization and coordination of the entire supply chains. For this purpose, a time varying input-output model with stochastic extension had been presented which can be used to simulate the supply chain dynamics of J. curcas biofuel. The model incorporates various extensions to the basic Leontief input-output model such as non-square matrix requirement for the technology matrix, adapting behavior based on target and current production levels, a control matrix to intervene on undesirable dynamics, and a Gaussian stochastic parameter that simulates uncontrolled changes in the production capacity which may be brought up by natural calamities and market instabilities. Numerical simulations of two-sector case studies having behavioral matrix patterned after the broad interactions between various sectorial agents were able to replicate the general trends of J. curcas biodiesel supply chain. The coefficients of the control matrix used to eliminate oscillatory dynamics of the system made physical suggestions that are strikingly similar to the ones made by some researchers in the field. With the incorporation of stochastic extension, the model was able to make predictions about the relative extent on how different streams will be affected by sudden random changes that are brought into the system